Kyverno before 1.19.2 Cosign Identity Check Bypass via Empty SAN Certificates
Only affects Kyverno 1.19.1 and earlier with verifyImages rules that pin the signer by subject and a cosign attestor using a custom private trust root. Fixed in 1.19.2.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 1.19.2
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. Kyverno versions before 1.19.2 (affected: 1.19.1 and earlier). A verifyImages rule pins the image signer by subject or subjectRegExp. The cosign attestor is configured with a custom or private trust root (keyless.roots). The attacker must hold a leaf certificate issued from that configured trusted root.
- Last modified
- FIRST's estimate of the chance attackers exploit it in the next 30 days, updated daily.What do these mean? →
- 0.18% · 7th percentile
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 15/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
Kyverno contains an authentication bypass in its image verification that an attacker can reach over the network after a low-privilege login. By using a leaf certificate from a configured private trust root that has no Subject Alternative Name, the attacker can get malicious signed images admitted despite signer pinning.
Read the original description
Kyverno before 1.19.2 contains an authentication bypass in matchCertificateData that skips verifyImages subject and subjectRegExp checks when the signing certificate has no Subject Alternative Name. Attackers holding a leaf certificate from a configured private trust root can omit the SAN, set the expected Fulcio issuer OID, and sign malicious images that are admitted despite signer pinning.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure8/25Specific setups only, reachable over the network
- Reach?/20Unknown. No tracked technology or package matched
- Severity7.2/10CVSS 7.2
- No patch0/5No signal
What would change the score
- Would score about 65 if added to CISA KEV
- Would score about 60 if CISA's SSVC rates exploitation active
- Would score about 22 if CISA's SSVC rates it automatable
What to do
Check whether your setup matches what the bug needs.
Kyverno versions before 1.19.2 (affected: 1.19.1 and earlier). A verifyImages rule pins the image signer by subject or subjectRegExp. The cosign attestor is configured with a custom or private trust root (keyless.roots). The attacker must hold a leaf certificate issued from that configured trusted root.Upgrade to a fixed version: 1.19.2.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- kyverno kyverno
fixed in 1.19.2
Evidence 2
- Advisory
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-122318
Is CVE-2026-122318 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
Kyverno can admit images signed by an attacker who holds a leaf certificate from a configured private trust root, even when the rule pins the signer by subject or subjectRegExp. The signer pin does not stop these malicious images.Source: vulncheck.com, github.com
Which versions are affected by CVE-2026-122318?
kyverno: before 1.19.2.Source: cve.now feed data
Am I affected, and how do I check?
Kyverno versions before 1.19.2, meaning 1.19.1 and earlier. The setup also needs a verifyImages rule that pins the signer by subject or subjectRegExp, and a cosign attestor configured with a custom trust root under keyless.roots. To check, look at the installed Kyverno version and whether the verifyImages attestors use keyless.roots.Source: vulncheck.com, github.com
How do I fix CVE-2026-122318?
Upgrade Kyverno to 1.19.2 or later, which fixes the bypass.Source: vulncheck.com, github.com